Powerwall on Ontario’s Ultra-Low Overnight: the 10× spread
In plain English: Ontario’s regulated ULO plan — 3.9¢ overnight, 39.1¢ on weekday evenings, the same published prices for every household on it.
Most rate plans give a battery a few cents of spread to work with. ULO hands it a canyon: overnight power at a tenth of the evening price, province-wide, set by the regulator. This is the strongest Powerwall arbitrage plan SolDial serves anywhere.
The plan at a glance
| Period | Hours | Rate |
|---|---|---|
| Ultra-low overnight | 11 PM–7 AM, every day | 3.9¢/kWh |
| On-peak | 4–9 PM weekdays | 39.1¢/kWh |
| Mid-peak | 7 AM–4 PM & 9–11 PM weekdays | 24.0¢/kWh |
| Weekend off-peak | 7 AM–11 PM weekends | 7.6¢/kWh |
OEB prices for the Nov 2025–Oct 2026 period, before HST and the Ontario Electricity Rebate. The OEB resets rates each May 1 and Nov 1 — check after those dates.
What this plan means for a Powerwall
Fill the battery at 3.9¢ every night with grid charging enabled, then spend it where power costs ten times more. Even after the battery’s ~10% round-trip loss, a kWh bought overnight and spent at 5 PM nets about 35¢ of value — a 13.5 kWh Powerwall cycling daily through the weekday peak moves real money every single day, with or without sunshine. That last part matters in an Ontario winter: this is one of the few plans where the battery keeps earning in January.
Solar households: Ontario’s net metering credits exports as kWh, but a kWh exported at midday offsets mid-peak value while a kWh held and spent at 6 PM offsets on-peak. Self-use through the evening beats export here.
The automations worth having
A nightly grid-charge that tops the pack inside the 11 PM–7 AM window; evening coverage that keeps the house on battery through 4–9 PM with a reserve floor for outages; an EV rule that moves car charging into the ultra-low window (the same 10× math applies to the car); and a rate-season reminder — when the OEB resets prices in May and November, your plan in SolDial should follow.
How SolDial runs ULO
The Ontario ULO preset ships in SolDial’s Utility Rates screen with the exact OEB windows and prices — pick it, confirm, done. Energy Autopilot then builds the cycle above around your actual usage, and Saved by SolDial counts the measured result, only when provable.
Does this apply to my exact situation?
Plans vary by region, retailer, and season, and rates get revised. SolDial recomputes the strategy — and the honest savings math — from your plan as you set it in the app, not a blog’s snapshot. If your plan differs from this page, the app follows your plan.